There are a number of micro-batteries that are designed to be implantable or otherwise associated with a medical or other device that require a power source for operation. Many of these micro-batteries are customized for the particular device in that their shape and power output match the particular device requirements. Thus, these custom designed micro-batteries cannot generally be utilized in devices they were not designed for as there are associated fit and power deficiencies. For purposes of this specification, a micro-battery is defined by its relatively small dimensions. Specifically, at least one dimension (that it the length, width or thickness of the battery) shall be less than one millimeter (1.0 mm), and a second dimension shall be less than one centimeter (1.0 cm).
Micro-batteries used in ocular medical devices can have unique and challenging requirements such as the need for flexibility, biocompatibility, and the associated in vivo environment. A contact lens using a micro-battery requires the battery to possess the qualities of the lens by having a long shelf life, have a measure of flexibility and being able to operate after being manipulated, and be biocompatible for the time period starting with lens manufacturing through the usage lifetime of the lens. This time period exposes the micro-battery to the saline within the lens, and the micro-battery must not only maintain its capacity and ability to provide the required power to the lens, but also be adequately sealed so as to prevent leaching of the battery components. The dimensions of a micro-battery makes isolation of the battery components particularly challenging as the surface area to volume ratio of the micro-battery can be very high.
Many micro-batteries, especially those mass-produced or those needing biocompatibility are encased in rigid exteriors. This rigidity makes it difficult for these micro-batteries to fit in any device which they are not designed for. In addition, their rigidity typically does not allow such batteries to be utilized in flexible devices.
Micro-batteries with flexible packaging or non-rigid exteriors have very little flexibility, and most often the internal construction of the micro-battery does not allow the battery to be bent or twisted. Batteries utilizing conductive traces require both flexible traces and flexible substrates on which to support the trace. Such flexibility is not found in materials compatible with an oxidizing battery environment. Instead, the batteries of the prior art are typically constructed to be generally immobile after being manufactured. Movement of the battery can adversely affect connections, sealing of the exterior and otherwise affect the proper operation of the battery.
There exists a need for a micro power supply that is biocompatible, can be used in medical and other small devices, and that is capable of repeated or continuous operation by providing required energy while the device is being, bent, flexed or otherwise manipulated and after such manipulation.